However, Downing Street is already playing for time — which is why the vote on this has been delayed to the autumn. They emphasise that they are listening before legislating, which indicates that a change in the policy might well be on the way. I understand No10 has already asked the Treasury for more details on how it works.

“George knocked this back several times,” one Government source tells me, while one Cabinet minister wonders why on earth Hammond is doing something so politically toxic as breaking a manifesto promise for “£145million — small change”.

Mrs May’s team have their criticisms of Hammond too. One Downing Street source complains that the

Treasury mishandled the briefing around the Budget, while one May ally says the Treasury’s ham-fisted attempt to claim the policy fits with the Tories’ no-tax-rise promise “just winds people up”.

Far better, they argue, to concentrate on the fairness argument, as Mrs May did on Thursday night.

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Theresa May's team have criticised Hammond too saying that the Treasury has mishandled briefings and that their policies will just wind people up

Downing Street is waiting to see how the situation develops. One senior source tells me: “The first thing you’ve got to do when there’s big concern is explain yourself better.”

But if the explanation doesn’t calm the anger, and considering how strongly Tories feel about this issue it is unlikely to, then No10 will look at ways to mitigate the policy.

Their fear is that if the majority drops significantly, and particularly if it is down to single figures, the

Lords will insist on coming back for another go.

This would hold up the Brexit Bill and threaten Mrs May’s chances of meeting her end of March deadline for triggering Article 50.

Tories plot to thwart Scots polls

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Nicola Sturgeon may be asked to wait until after Brexit to hold a second referendum for Scottish referendum

DOWNING STREET and the Scottish Tories think they might have hit upon a way to frustrate Nicola Sturgeon’s plans for a second Scottish independence referendum.

They won’t refuse outright any Sturgeon demand for a new poll. But they will instead insist that it waits until after Brexit and, crucially, after it is clear what relationship with the EU an independent Scotland could have.

They calculate that this would mean that the referendum could not take place until 2021. The result of this: Nicola Sturgeon’s Scottish Nationalists and their Green allies would have to win another majority in the Scottish parliamentary elections to hold a referendum.

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Mrs Sturgeon would struggle to do this. By 2021 the SNP will have been in power at Holyrood for 14 years – and the laws of political gravity mean that few parties are popular after that long in office.

Second, Scots, including some of those who would vote Yes to independence, aren’t keen on another referendum.

They know the division that the last one caused and are worried about the economic uncertainty it would create. With the polls suggesting Scots are split 50-50 on independence, the safest thing for the UK Government to do is to find a way of preventing a second referendum that doesn’t just look like a refusal to have one on the grounds they might lose.

The 2021 strategy is the best approach anyone has come up with so far.

Chancellor 'Left to swing' by PM

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Theresa May's 'sink or swim' approach extends to Chancellor, Philip Hammond even after the newly announced budget plans

‘WITH this No10, if you get into trouble – whether it is your own fault or not – you’re left to swing in the wind,” complains one Cabinet minister.

“It is a sink-or-swim approach,” says one senior minister – and the events of the past few days have made clear that it even “extends to the Chancellor”.

Mrs May’s approach is understandable, it keeps her above the day-to-day fray. Margaret Thatcher used to do much the same.

One Cameron confidant tells me that the Government is paying the price for “believing its own hype”.

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Tories are concerned as they claim that the Prime Minister will not stand by MPs if they get into trouble whether they deserve it or not

Hammond himself is coming in for flak. One former Cabinet colleague says: “I’ve heard enough acerbic comments from him about other people’s difficulties. There are lots of people in Whitehall saying, ‘See, it’s not as simple as you think.’”

But one Hammond ally says this row is “the legacy of clever Dick George”.

He argues: “Philip and Theresa wouldn’t have put in the manifesto what Dave and George did.”